SDL_image: Document the animation delay units (168ff)

SDL Commits
1 
From 168ff36f9da23a0490dab190ba37919b64bb2715 Mon Sep 17 00:00:00 2001
From: Sam Lantinga <[EMAIL REDACTED]>
Date: Tue, 22 Apr 2025 10:40:00 -0700
Subject: [PATCH] Document the animation delay units

Fixes https://github.com/libsdl-org/SDL_image/issues/550

(cherry picked from commit a8d223f9ead4639cf07ad2612bfe883a2a6093b8)
---
 include/SDL_image.h | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/include/SDL_image.h b/include/SDL_image.h
index 82398545c..cbf25953c 100644
--- a/include/SDL_image.h
+++ b/include/SDL_image.h
@@ -2039,16 +2039,17 @@ extern DECLSPEC int SDLCALL IMG_SaveJPG(SDL_Surface *surface, const char *file,
 extern DECLSPEC int SDLCALL IMG_SaveJPG_RW(SDL_Surface *surface, SDL_RWops *dst, int freedst, int quality);
 
 /**
- * Animated image support.
+ * Animated image support
  *
- * Currently only animated GIFs are supported.
+ * Currently only animated GIFs and WEBP images are supported.
  */
 typedef struct IMG_Animation
 {
-	int w, h;
-	int count;
-	SDL_Surface **frames;
-	int *delays;
+    int w;                  /**< The width of the frames */
+    int h;                  /**< The height of the frames */
+    int count;              /**< The number of frames */
+    SDL_Surface **frames;   /**< An array of frames */
+    int *delays;            /**< An array of frame delays, in milliseconds */
 } IMG_Animation;
 
 /**